1. Field of the Invention
The present invention relates to a filament winding apparatus equipped with a helical winding device, and a modified form of a supply structure of a fiber bundle configured by a guide ring and a guide tube arranged in a ring thereof.
2. Description of the Related Art
A pressure container is formed through a filament winding method by a reinforcement layer wound around a circumferential surface of a hollow mandrel. In most cases, the mandrel integrally includes a middle cylindrical part continuing to dome parts at both left and right ends of the cylindrical part. A fiber bundle is wound around the cylindrical part and the left and right dome parts to form the reinforcement layer. The fiber bundle is supplied to the mandrel by way of numerous guide bodies (see, for example, Japanese Laid-Open Patent Publication No. 2004-314550). The guide body is arranged on an array head that slides in a reciprocating manner along an axis center of the mandrel, and is arranged in a dispersed manner around the mandrel. The fiber bundle is moved and guided by the guide body, and is supplied to the mandrel by way of a fiber-spreading ring that is concentric with the mandrel. During the operation of the winding apparatus, the array head is reciprocated while rotatably driving the mandrel, so that the fiber bundle supplied from the guide tube is wound around the mandrel, thereby forming the reinforcement layer.
The supply position of the fiber bundle with respect to the mandrel may be changeable (see, for example, Japanese Laid-Open Patent Publication No. 2005-154908). Here, the supply position of the fiber bundle is changed by rotationally displacing a yarn feeding unit between a case of winding the fiber bundle around the cylindrical part of the mandrel and a case of winding the fiber bundle around the dome part. The yarn feeding unit is configured by a supporting part supported in a freely rotating manner, an exit guide arranged at a distal end of the supporting part, and the like. The supply position of the fiber bundle can be changed by the rotationally displaced amount of the exit guide. Similarly, it is known to displace a feed eye that supplies and guides the fiber bundle towards the mandrel in a radius direction of the mandrel at the dome part of the mandrel (see, for example, Japanese Laid-Open Patent Publication No. 2002-46940). In either case, the displacement amount of the exit guide and the feed eye is very limited.
The winding apparatuses according to Japanese Laid-Open Patent Publication Nos. 2005-154908 and 2002-46940 wind the fiber bundle around a circumferential surface of a mandrel by the cooperative action of the rotatably driven mandrel, and one yarn supply unit (or feed eye) reciprocated along the axis center of the mandrel. Thus, forming a reinforcement layer by repeatedly performing hoop winding and helical winding requires a great amount of time, and the pressure container is thereby not efficiently formed. By contrast, in Japanese Laid-Open Patent Publication No. 2004-314550, a group of fiber bundles are simultaneously supplied to the mandrel, such that the winding process is performed in a shorter period of time and the pressure container is more efficiently manufactured.
In Japanese Laid-Open Patent Publication No. 2004-314550, however, the supply position of the fiber bundle with respect to the mandrel is always constant for the cylindrical and dome parts since the fiber bundle is supplied to the mandrel by way of a fiber-spreading ring. At the semispherical dome part, the diameter of the mandrel gradually decreases towards a mouth part, and the winding trajectory of the fiber bundle tends to shift to the mouth part side. Thus, it becomes difficult to orderly wind the group of fiber bundles around the dome part.